In situ-XAS and catalytic study of acrolein hydrogenation over silver catalyst: Control of intramolecular selectivity by the pressure

Abstract

The gas phase hydrogenation of acrolein over 7.5% Ag/SiO 2 has been studied in a broad pressure range from 7.5 mbar to 20 bar. Higher pressures favour the formation of allyl alcohol (selectivities up to 42 %), whereas at low pressures propionaldehyde is by far the main product. In situ-XAS has been performed at 7.5 mbar in order to gain insight into the interaction of acrolein with Ag(111). Hydrogenated propionaldehyde-like surface species could be detected which orientated parallel to the surface. The observed intermediate correlates perfectly with the online catalytic data.

Bridging the pressure and materials gap: in-depth characterisation and reaction studies of silver-catalysed acrolein hydrogenation

“…Additionally, a dependence on the reaction pressure has been found down to 7.5 mbar [19]. We have now investigated this pressure dependence in much more detail, especially in the low-pressure region.…”

“…Silver single-crystals (Ag(111), Ag(100)), polycrystalline Ag foil and supported catalyst (7.5Ag/SiO 2 -IW) were used to learn about the interaction of acrolein with silver and about the orientation of acrolein on well-oriented surfaces in the presence of reaction mixture (0.01 mbar AC + 7.48 mbar H 2 ) (see Ref. [19] for preliminary results on the Ag(111) phase). Using XAS gas-phase detection (see 2.4), the gas-phase composition has been checked with XAS during the in situ-experiments.…”

Synthesis, Crystal Structure, and Catalytic Properties of MgCo6Ge6

“…through basic zeolites and graphite), steric constraints in the metal environment, strong metal-support interactions (SMSI), selective poisoning, substituents on the C=C bond, solvents, and pressure effects. [3][4][5] The influence of these parameters can be also found in the selective hydrogenation of citral in numerous studies in the past few years.…”

In situ X-ray investigations on AgIn/SiO2 hydrogenation catalysts

“…285 eV, C K-edge), we were able to show that at low pressures (7.5 mbar) acrolein adsorbs in a flat manner on the catalyst surface [14,15].…”

“…On the other hand, when working in capillary geometry, to our experience high flow rates can not be achieved due to the pressure drop in the capillary filled with powder. Since the hydrogenation of acrolein over silver is strongly pressure dependent [13][14][15], undefined pressure drops have to be avoided.…”